CN113493867A - Method for smelting low-phosphorus steel from semisteel - Google Patents
Method for smelting low-phosphorus steel from semisteel Download PDFInfo
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- CN113493867A CN113493867A CN202110473733.7A CN202110473733A CN113493867A CN 113493867 A CN113493867 A CN 113493867A CN 202110473733 A CN202110473733 A CN 202110473733A CN 113493867 A CN113493867 A CN 113493867A
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- slag
- semisteel
- steel
- phosphorus
- molten steel
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/28—Manufacture of steel in the converter
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C1/00—Refining of pig-iron; Cast iron
- C21C1/02—Dephosphorising or desulfurising
- C21C1/025—Agents used for dephosphorising or desulfurising
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/56—Manufacture of steel by other methods
- C21C5/562—Manufacture of steel by other methods starting from scrap
- C21C5/565—Preheating of scrap
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0056—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00 using cored wires
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/06—Deoxidising, e.g. killing
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/064—Dephosphorising; Desulfurising
- C21C7/0645—Agents used for dephosphorising or desulfurising
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Treatment Of Steel In Its Molten State (AREA)
Abstract
The invention discloses a method for smelting low-phosphorus steel from semisteel, which comprises the following steps: s1, adding small pieces or strip-shaped steel scraps into the semisteel in the converter, and carrying out pretreatment desulfurization on the semisteel in the converter until the sulfur content is 0.01-0.005%; s2, after the scrap steel is completely melted, adding lime and dolomite in a proportion of 1-5% per minute for slagging, and uniformly covering the surface of the semisteel in the converter with the lime and the dolomite; s3, supplying oxygen to the converter, and pouring 40-60% of slag when the temperature of the semisteel is 1540-1600 ℃ and the alkalinity of the slag is 4-5; the invention has the beneficial effects that: 1. the operation mode of semisteel slag retention promotes the rapid formation of slag at the initial stage of smelting, and improves the dephosphorization rate; 2. controlling the alkalinity of the slag, improving the end point carbon content and the tapping temperature, reducing the oxygen property of the slag and improving the fluidity of the slag; 3. the pretreatment is carried out with deep desulfurization, thereby reducing the refining treatment burden and the deep reduction force in the refining process.
Description
Technical Field
The invention relates to the field of low-phosphorus steel, in particular to a method for smelting low-phosphorus steel from semisteel.
Background
When the prior steel plant produces low-phosphorus steel grades such as ER50-6, the adopted process is as follows: high-alkalinity slag is produced from the large slag charge, the tapping endpoint is low-temperature and low-carbon, slag is blocked by using a slag blocking ball during tapping, and white slag is produced for desulfurization after external refining treatment; the practical operation shows that the prior process has the following defects: (1) the semi-steel after vanadium extraction has low Si and Mn slagging elements, difficult slagging in the smelting process and poor dephosphorization effect, the content of once poured phosphorus is more than 0.015 percent, (2) because a large slag charge slagging mode is adopted and the low-carbon steel tapping is adopted, the tapping temperature is low, the slag is viscous and has higher oxygen property, slag stopping failure is often caused in the steel tapping process, high-oxidizing slag falls into molten steel to cause molten steel rephosphorization, the rephosphorization amount of the molten steel reaches 0.005 percent, and (3) the molten steel needs to be refined outside the furnace, the refining process is deep reduction, phosphorus in the slag can be partially reduced into the molten steel, and the phosphorus control difficulty of the molten steel is high.
Disclosure of Invention
The invention aims to provide a method for smelting low-phosphorus steel from semisteel, which aims to solve the problems in the background technology.
In order to achieve the purpose, the invention provides the following technical scheme: a method for smelting low-phosphorus steel from semisteel comprises the following steps:
s1, adding small pieces or strip-shaped steel scraps into the semisteel in the converter, and carrying out pretreatment desulfurization on the semisteel in the converter until the sulfur content is 0.01-0.005%;
s2, after the scrap steel is completely melted, adding lime and dolomite in a proportion of 1-5% per minute for slagging, and uniformly covering the surface of the semisteel in the converter with the lime and the dolomite;
s3, supplying oxygen to the converter, and pouring 40-60% of slag when the temperature of the semisteel is 1540-1600 ℃ and the alkalinity of the slag is 4-5;
s4, further raising the temperature of the semisteel to 1650-1680 ℃, improving the fluidity of the slag, reducing the oxygen content of the molten steel, and adding a slag modifier;
s5, tapping the semi-steel, blocking slag through a slag blocking dart, wherein the slag blocking amount is more than 95%, and obtaining molten steel after tapping;
s6, performing external refining on the molten steel until the sulfur content is less than 0.01%, controlling the FeO and MnO content of the refining slag to be 1% -2%, and reducing the deep reduction force to obtain the finished low-phosphorus steel with the phosphorus content of less than 0.013%.
Preferably, the molten steel pretreatment desulfurization of S1 is to desulfurize molten steel by feeding iron sheet-coated deoxidizing, desulfurizing and fine-tuning component powders or directly feeding aluminum wire, carbon wire, etc. into a ladle through a wire feeder.
Preferably, the slag in the S1 comprises, by weight, 20-25% of active lime, 25-35% of high-magnesium lime, 10-15% of bauxite, 5-15% of ferric oxide, 12-15% of dolomite and 5-10% of coarse aluminum.
Preferably, in S2, oxygen is supplied through an oxygen lance, and the oxygen pressure of the oxygen lance is 0.80 MP-0.90 MP.
Preferably, the slag modifier of S3 comprises, by weight, 25-35 wt% of calcium oxide, 15-20 wt% of magnesium oxide, 11-15 wt% of silicon dioxide and 6-10 wt% of silicon monoxide, and the balance of impurities.
Preferably, in step S4, the slag stopper is put into the ladle before tapping the molten steel, and the slag stopper is used to stop the steel slag by using the volume density difference between the molten steel, the steel slag and the slag stopper, so as to tap the relatively pure molten steel.
Preferably, the rephosphorization ratio of semisteel at the time of tapping of S4 is less than 0.003%, and the rephosphorization ratio of S5 molten steel refined outside the furnace is 0.
Preferably, the S5 external refining is carried out under the vacuum condition that the vacuum degree is not higher than 8 kPa, and the molten steel obtained after blowing is firstly contacted with the carbonaceous material and then contacted with a non-carbonaceous material deoxidizer so as to deoxidize the molten steel.
Compared with the prior art, the invention has the beneficial effects that:
1. the operation mode of semisteel slag retention promotes the rapid formation of slag at the initial stage of smelting, and improves the dephosphorization rate;
2. controlling the alkalinity of the slag, improving the end point carbon content and the tapping temperature, reducing the oxygen property of the slag and improving the fluidity of the slag;
3. the pretreatment is carried out with deep desulfurization, thereby reducing the refining treatment burden and the deep reduction force in the refining process.
Detailed Description
The invention provides a technical scheme that: a method for smelting low-phosphorus steel from semisteel comprises the following steps:
s1, adding small pieces or strip-shaped steel scraps into the semisteel in the converter, and carrying out pretreatment desulfurization on the semisteel in the converter until the sulfur content is 0.01-0.005%;
s2, after the scrap steel is completely melted, adding lime and dolomite in a proportion of 1-5% per minute for slagging, and uniformly covering the surface of the semisteel in the converter with the lime and the dolomite;
s3, supplying oxygen to the converter, and pouring 40-60% of slag when the temperature of the semisteel is 1540-1600 ℃ and the alkalinity of the slag is 4-5;
s4, further raising the temperature of the semisteel to 1650-1680 ℃, improving the fluidity of the slag, reducing the oxygen content of the molten steel, and adding a slag modifier;
s5, tapping the semi-steel, blocking slag through a slag blocking dart, wherein the slag blocking amount is more than 95%, and obtaining molten steel after tapping;
s6, performing external refining on the molten steel until the sulfur content is less than 0.01%, controlling the FeO and MnO content of the refining slag to be 1% -2%, and reducing the deep reduction force to obtain the finished low-phosphorus steel with the phosphorus content of less than 0.013%.
Further, the molten steel pretreatment desulfurization of S1 is to feed iron sheet-coated deoxidizing, desulfurizing and fine-tuning component powder into a ladle through a wire feeder, or to directly feed an aluminum wire, a carbon wire, and the like to desulfurize molten steel.
Further, the slag in the S1 comprises, by weight, 20-25% of active lime, 25-35% of high-magnesium lime, 10-15% of bauxite, 5-15% of ferric oxide, 12-15% of dolomite and 5-10% of coarse aluminum.
In S2, oxygen is supplied through an oxygen lance, and the oxygen pressure of the oxygen lance is 0.80 MP-0.90 MP.
Furthermore, the slag modifier of S3 comprises, by weight, 25-35 wt% of calcium oxide, 15-20 wt% of magnesium oxide, 11-15 wt% of silicon dioxide, 6-10 wt% of silicon monoxide, and the balance impurities.
Further, in step S4, before tapping, the slag stopper is put into the ladle, and the slag stopper is used to block the steel slag by using the volume density difference between the molten steel, the steel slag and the slag stopper, so as to tap the relatively pure molten steel.
Further, the rephosphorization rate of semisteel at the time of tapping of S4 is less than 0.003%, and the rephosphorization rate of S5 molten steel refined outside the furnace is 0.
Further, the S5 external refining is carried out under the vacuum condition that the vacuum degree is not higher than 8 kPa, and the refining is carried out, and the molten steel obtained after the blowing is firstly contacted with the carbonaceous material and then contacted with a non-carbonaceous material deoxidizer, so as to deoxidize the molten steel.
Specifically, when the invention is used, small pieces or strip-shaped steel scraps are added into semisteel in a converter and the semisteel is heated, after the steel scraps are melted, powder of deoxidation, desulfurization and fine adjustment components wrapped by iron sheets is fed into a ladle through a wire feeding machine or an aluminum wire, a carbon wire and the like are directly fed into the ladle to desulfurize the molten steel until the sulfur content is 0.01%, after the steel scraps are completely melted, lime and dolomite are added according to the proportion of 1-5% per minute to carry out slagging, the lime and the dolomite are uniformly covered on the surface of the semisteel in the converter, then oxygen is supplied to the converter through a supply gun, when the temperature of the semisteel is 1560 ℃ and the alkalinity of the slag is 4-5, 50% of the slag is poured out, then the oxygen supply gun is continuously used for supplying oxygen, the temperature of the semisteel is further raised to 1670 ℃, the fluidity of the slag is improved, the oxygen content of the molten steel is reduced, and a slag adjusting agent is added, tapping the semisteel, putting a slag dart into a steel ladle before tapping water, blocking the steel slag by the slag dart by utilizing the volume density difference among the molten steel, the steel slag and the slag dart, wherein the slag blocking amount is more than 95%, obtaining molten steel after tapping, the rephosphorization rate of the semisteel of the molten steel is less than 0.003%, then carrying out external refining on the molten steel under the vacuum condition that the vacuum degree is not more than 8 kilopascals, contacting the molten steel obtained after blowing with a carbonaceous material, and then contacting with a non-carbonaceous material deoxidizer to deoxidize the molten steel, wherein the sulfur content is less than 0.01%, the FeO + MnO content is controlled to be 1-2%, and the deep reduction force is reduced to obtain the finished low-phosphorus steel with the phosphorus content of less than 0.013%;
according to the invention, by adopting the operation mode of semi-steel slag remaining, good conditions are provided for the formation of the initial slag of the semi-steel smelting of the converter, the initial slag can be quickly formed within 3min of blowing, the slag melting effect in the process is greatly improved, and the dephosphorization rate improvement effect is obvious. The content of the first-grade phosphorus is less than or equal to 0.010 percent; the fluidity of the slag is improved by raising the temperature of the molten steel, the slag stopping success rate of tapping reaches 95 percent, and the rephosphorization in the tapping process is less than or equal to 0.003 percent; the average sulfur content of the molten steel in the refining furnace is less than 0.010 percent, the desulfurization burden of the refining furnace is reduced, and the molten steel is not rephosphorized in the refining process; the phosphorus content of the low-phosphorus steel finished product averagely reaches 0.013 percent, and the proportion of less than 0.010 percent can reach 20 percent.
| Index (I) | Content (wt.) |
| Initial slag formation time (min) | 2 |
| Content of phosphorus (%) | 0.010 |
| Slag stopping success rate (%) | 95 |
| Rephosphorization in tapping (%) | 0.003 |
| Refining process rephosphorization (%) | 0 |
| Phosphorus content (%) | 0.013 |
The above is the detection data of the finished steel.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (8)
1. The method for smelting the low-phosphorus steel from the semisteel is characterized by comprising the following steps of:
s1, adding small pieces or strip-shaped steel scraps into the semisteel in the converter, and carrying out pretreatment desulfurization on the semisteel in the converter until the sulfur content is 0.01-0.005%;
s2, after the scrap steel is completely melted, adding lime and dolomite in a proportion of 1-5% per minute for slagging, and uniformly covering the surface of the semisteel in the converter with the lime and the dolomite;
s3, supplying oxygen to the converter, and pouring 40-60% of slag when the temperature of the semisteel is 1540-1600 ℃ and the alkalinity of the slag is 4-5;
s4, further raising the temperature of the semisteel to 1650-1680 ℃, improving the fluidity of the slag, reducing the oxygen content of the molten steel, and adding a slag modifier;
s5, tapping the semi-steel, blocking slag through a slag blocking dart, wherein the slag blocking amount is more than 95%, and obtaining molten steel after tapping;
s6, performing external refining on the molten steel until the sulfur content is less than 0.01%, controlling the FeO and MnO content of the refining slag to be 1% -2%, and reducing the deep reduction force to obtain the finished low-phosphorus steel with the phosphorus content of less than 0.013%.
2. The method for smelting the low-phosphorus steel from the semisteel according to claim 1, which is characterized by comprising the following steps of: and the molten steel pretreatment desulfurization of S1 is to feed iron sheet-coated deoxidizing, desulfurizing and fine-tuning component powder into a steel ladle through a wire feeding machine or directly feed an aluminum wire, a carbon wire and the like to desulfurize the molten steel.
3. The method for smelting the low-phosphorus steel from the semisteel according to claim 2, characterized by comprising the following steps of: the slag in the S1 comprises, by weight, 20-25% of active lime, 25-35% of high-magnesium lime, 10-15% of bauxite, 5-15% of ferric oxide, 12-15% of dolomite and 5-10% of coarse aluminum.
4. The method for smelting the low-phosphorus steel from the semisteel according to claim 1, which is characterized by comprising the following steps of: in the S2, oxygen is supplied through an oxygen blowing lance, and the oxygen pressure of the oxygen blowing lance is 0.80 MP-0.90 MP.
5. The method for smelting the low-phosphorus steel from the semisteel according to claim 1, which is characterized by comprising the following steps of: the slag modifier of S3 comprises, by weight, 25-35 wt% of calcium oxide, 15-20 wt% of magnesium oxide, 11-15 wt% of silicon dioxide, 6-10 wt% of silicon monoxide, and the balance of impurities.
6. The method for smelting the low-phosphorus steel from the semisteel according to claim 1, which is characterized by comprising the following steps of: and S4, before tapping, the slag dart is put into a steel ladle, and the slag dart is used for stopping the steel slag by utilizing the volume density difference among the molten steel, the steel slag and the slag dart to flow out relatively pure molten steel.
7. The method for smelting the low-phosphorus steel from the semisteel according to claim 1, which is characterized by comprising the following steps of: and the rephosphorization rate of semisteel is less than 0.003 percent when the S4 steel is tapped, and the rephosphorization rate of the S5 molten steel refined outside the furnace is 0.
8. The method for smelting the low-phosphorus steel from the semisteel according to claim 1, which is characterized by comprising the following steps of: and the S5 external refining is carried out under the vacuum condition that the vacuum degree is not higher than 8 kilopascals and is refined, and the molten steel obtained after blowing is firstly contacted with a carbonaceous material and then contacted with a non-carbonaceous material deoxidizer so as to deoxidize the molten steel.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110473733.7A CN113493867A (en) | 2021-04-29 | 2021-04-29 | Method for smelting low-phosphorus steel from semisteel |
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| CN202110473733.7A CN113493867A (en) | 2021-04-29 | 2021-04-29 | Method for smelting low-phosphorus steel from semisteel |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101696462A (en) * | 2009-11-03 | 2010-04-21 | 攀钢集团研究院有限公司 | Method for producing low phosphorus steel by smelting semisteel |
| CN101962700A (en) * | 2010-07-29 | 2011-02-02 | 攀钢集团有限公司 | Method for smelting low-phosphorous molten steel by utilizing semisteel |
| CN103194564A (en) * | 2013-03-25 | 2013-07-10 | 济钢集团有限公司 | Process for producing ultra-low phosphorus steel |
| CN105861775A (en) * | 2015-01-23 | 2016-08-17 | 鞍钢股份有限公司 | Smelting process for ultra-low phosphorus steel with high nickel content |
| CN111349747A (en) * | 2020-05-06 | 2020-06-30 | 攀钢集团西昌钢钒有限公司 | Converter steelmaking method with semisteel slag left completely |
-
2021
- 2021-04-29 CN CN202110473733.7A patent/CN113493867A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101696462A (en) * | 2009-11-03 | 2010-04-21 | 攀钢集团研究院有限公司 | Method for producing low phosphorus steel by smelting semisteel |
| CN101962700A (en) * | 2010-07-29 | 2011-02-02 | 攀钢集团有限公司 | Method for smelting low-phosphorous molten steel by utilizing semisteel |
| CN103194564A (en) * | 2013-03-25 | 2013-07-10 | 济钢集团有限公司 | Process for producing ultra-low phosphorus steel |
| CN105861775A (en) * | 2015-01-23 | 2016-08-17 | 鞍钢股份有限公司 | Smelting process for ultra-low phosphorus steel with high nickel content |
| CN111349747A (en) * | 2020-05-06 | 2020-06-30 | 攀钢集团西昌钢钒有限公司 | Converter steelmaking method with semisteel slag left completely |
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